Male sterilization is generally accomplished by vasectomy in which the vas deferens is surgically interrupted by ligation or by cauterization. This procedure generally requires surgical opening of the scrotum. Although vasectomy is simpler, safer and less expensive than female sterilization, far fewer male sterilizations are performed world-wide than female sterilizations due, at least in part, to an excessive apprehension of the pain that might be associated with such a procedure. In addition, in many parts of the world, males equate any surgical procedure performed on male genitals to castration.
One example of a patent which shows apparatus and methods for performing vasectomy procedures in which the scrotum is surgically opened is U.S. Pat. No. 4,103,688 to Edwards. In Edwards, an incision is first made in the scrotum and then the vas deferens is severed. Next, the uninsulated tip of a unipolar needle electrode is sequentially inserted into the openings of the severed ends of the vas deferens to cauterize the ends. Similarly, in U.S. Pat. No. 4,034,762 to Cosens, et al., incisions are first made in the scrotum and in the vas deferens and then a bipolar needle electrode is inserted into the severed ends of the vas deferens to seal the same via cauterization.
In order to overcome male fears and phychological misgivings associated with surgical vasectomies, percutaneous vasectomy procedures have been developed for, in one case, cauterizing the vas deferens and, in another case, chemically sealing the vas deferens. U.S. Pat. No. 4,269,174 to Adair is an example of a percutaneous vasectomy method and apparatus is which the vas deferens of a male patient is cauterized without making a surgical incision in the scrotum wall. In the Adair patent a sharp-tipped, hollow needle which serves both as a first electrode and as a means by which an anesthetic is transferred from a container into the vas deferens, is inserted through the scrotum wall and into the interior of the vas deferens. After the anesthetic has been introduced into the vas deferens, the anesthetic container is removed from the needle, without withdrawing the needle from the vas deferens, and a second, blunt-tipped, electrode is inserted telescopically through the first needle into the vas deferens so as to protrude therefrom. Thereafter, the electrodes are energized with suitable cauterizing energy, sealing the vas deferens, and the two electrodes are then removed therefrom. The foregoing percutaneous vasectomy procedure has not proven to be entirely successful due to the fact that, in many cases, it fails to attain azoospermia. The high failure rate is believed to result from difficulty associated with placing the tip of the bipolar needle into the vas deferens since the bipolar needle has a diameter of about 1.6 mm and the average diameter of the lumen of the human vas deferens is about 0.55 mm, distendable to about 1.2 mm.
Yet another example of a percutaneous vasectomy procedure utilizing a cauterizing needle electrode which is inserted into the vas deferens is given in an article entitled "Percutaneous Fulgarization of Vas", by S. L. Agarwal, et al., in Indian Journal of Medical Research 78, October 1983, pp. 547-551 In this procedure a 4 cm long, 24 gauge, insulated vasectomy needle is inserted into the vas deferens and then the vas deferens is cauterized by diathermy coagulation current applied through the vasectomy needle, using an electrosurgical cautery. Detailed steps of the procedure are not provided in the article and difficulties with respect to accurate placement of the vasectomy needle electrode within the vas deferens and the amount of time expended in performing this procedure would result from its use.
An example of a percutaneous vasectomy procedure in which the vas deferens of a male patient is chemically occluded or sealed without making a surgical incision in the scrotum wall is given in an article entitled "Clinical Application of Vas Deferens Puncture", by Li Shun-qiang, in the Chinese Medical Journal, 93(1):69-70, 1980. The same procedure is apparently presented in greater detail in a report entitled "Non-Operative Sterility Research With Intravasal Injecting Drug (Clinical Report)", by Li Shun-qiang and Zhu Jin-Bo, presented at the Expert Committee Meeting on Training For Voluntary Surgical Contraception, Rio de Janeiro, Brazil, Sept. 26-29, 1984. In this procedure the vas deferens is, under local anesthesia, initially fixed with a clamp and a first, sharp-tipped, vas deferens puncture needle is inserted perpendicularly into the lumen of the vas deferens through its anterior wall. The first needle is then replaced by a second, blunt-tipped, vas deferens injection needle which is passed through the puncture hole of the first needle. Then, 0.02 ml of a chemical sealant mixture (e.g., carbolic acid-n-butyl-cyanacrylaty) is injected into the vas deferens through the second needle to obliterate the lumen permanently. After about 20 seconds, the mixture coagulates and the second needle is withdrawn.
Although satisfactory results appear to have been achieved with the chemical occlusion process described above, the necessity for extensive toxicology studies and regulatory agency approval of chemical agents injected into the human vas deferens represents a significant impediment to near term adoption and use of the procedure in many countries of the world.
It is, therefore, a primary object of the present invention to provide an improved, currently acceptable, method of sealing a male vas deferens without incising the wall of the patient's scrotum.
Another object of the present invention is to provide an improved percutaneous vasectomy method in which a puncture passageway is made from the outer surface of the scrotum to the interior of the vas defens by a sharp-tipped needle which is thereafter withdrawn and replaced in the passageway by a narrower, blunt-tipped, cauterizing needle.
Further objects and advantages of this invention will become apparent as the following description proceeds.
Briefly stated, and in accordance with one embodiment of this invention, the method of closing the vas deferens to sterilize a male patient without incising the patient's scrotum comprises the steps of inserting a sharp-tipped needle having a first predetermined diameter into the scrotum of the male patient and through a wall of the vas deferens, the insertion forming a passageway from the surface of the scrotum to the interior of the vas deferens; removing the sharp-tipped needle from the vas deferens and the scrotum; inserting a blunt-tipped needle having a second predetermined diameter, less than the first predetermined diameter, through the passageway and into the interior of the vas deferens; activating a cauterizing element which includes the blunt-tipped needle for a selected period of time to cauterize and thereby close the vas deferens to sterilize the male patient; and removing the blunt-tipped needle from the vas deferens and scrotum.
As used herein, the term "needle" has reference not only to conventional, hollow, injection type needles but also to solid trocar puncture needles.